/*
 * Copyright (c) 2000 World Wide Web Consortium,
 * (Massachusetts Institute of Technology, Institut National de
 * Recherche en Informatique et en Automatique, Keio University). All
 * Rights Reserved. This program is distributed under the W3C's Software
 * Intellectual Property License. This program is distributed in the
 * hope that it will be useful, but WITHOUT ANY WARRANTY; without even
 * the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
 * PURPOSE.
 * See W3C License http://www.w3.org/Consortium/Legal/ for more details.
 */

package org.w3c.dom.events;

/**
 * The <code>Event</code> interface is used to provide contextual information 
 * about an event to the handler processing the event. An object which 
 * implements the <code>Event</code> interface is generally passed as the 
 * first parameter to an event handler. More specific context information is 
 * passed to event handlers by deriving additional interfaces from 
 * <code>Event</code> which contain information directly relating to the 
 * type of event they accompany. These derived interfaces are also 
 * implemented by the object passed to the event listener. 
 * <p>See also the <a href='http://www.w3.org/TR/2000/REC-DOM-Level-2-Events-20001113'>Document Object Model (DOM) Level 2 Events Specification</a>.
 * @since DOM Level 2
 */
public interface Event {
    // PhaseType
    /**
     * The current event phase is the capturing phase.
     */
    public static final short CAPTURING_PHASE           = 1;
    /**
     * The event is currently being evaluated at the target 
     * <code>EventTarget</code>.
     */
    public static final short AT_TARGET                 = 2;
    /**
     * The current event phase is the bubbling phase.
     */
    public static final short BUBBLING_PHASE            = 3;

    /**
     * The name of the event (case-insensitive). The name must be an XML name.
     */
    public String getType();

    /**
     * Used to indicate the <code>EventTarget</code> to which the event was 
     * originally dispatched. 
     */
    public EventTarget getTarget();

    /**
     * Used to indicate the <code>EventTarget</code> whose 
     * <code>EventListeners</code> are currently being processed. This is 
     * particularly useful during capturing and bubbling. 
     */
    public EventTarget getCurrentTarget();

    /**
     * Used to indicate which phase of event flow is currently being 
     * evaluated. 
     */
    public short getEventPhase();

    /**
     * Used to indicate whether or not an event is a bubbling event. If the 
     * event can bubble the value is true, else the value is false. 
     */
    public boolean getBubbles();

    /**
     * Used to indicate whether or not an event can have its default action 
     * prevented. If the default action can be prevented the value is true, 
     * else the value is false. 
     */
    public boolean getCancelable();

    /**
     *  Used to specify the time (in milliseconds relative to the epoch) at 
     * which the event was created. Due to the fact that some systems may 
     * not provide this information the value of <code>timeStamp</code> may 
     * be not available for all events. When not available, a value of 0 
     * will be returned. Examples of epoch time are the time of the system 
     * start or 0:0:0 UTC 1st January 1970. 
     */
    public long getTimeStamp();

    /**
     * The <code>stopPropagation</code> method is used prevent further 
     * propagation of an event during event flow. If this method is called 
     * by any <code>EventListener</code> the event will cease propagating 
     * through the tree. The event will complete dispatch to all listeners 
     * on the current <code>EventTarget</code> before event flow stops. This 
     * method may be used during any stage of event flow.
     */
    public void stopPropagation();

    /**
     * If an event is cancelable, the <code>preventDefault</code> method is 
     * used to signify that the event is to be canceled, meaning any default 
     * action normally taken by the implementation as a result of the event 
     * will not occur. If, during any stage of event flow, the 
     * <code>preventDefault</code> method is called the event is canceled. 
     * Any default action associated with the event will not occur. Calling 
     * this method for a non-cancelable event has no effect. Once 
     * <code>preventDefault</code> has been called it will remain in effect 
     * throughout the remainder of the event's propagation. This method may 
     * be used during any stage of event flow. 
     */
    public void preventDefault();

    /**
     * The <code>initEvent</code> method is used to initialize the value of an 
     * <code>Event</code> created through the <code>DocumentEvent</code> 
     * interface. This method may only be called before the 
     * <code>Event</code> has been dispatched via the 
     * <code>dispatchEvent</code> method, though it may be called multiple 
     * times during that phase if necessary. If called multiple times the 
     * final invocation takes precedence. If called from a subclass of 
     * <code>Event</code> interface only the values specified in the 
     * <code>initEvent</code> method are modified, all other attributes are 
     * left unchanged.
     * @param eventTypeArg Specifies the event type. This type may be any 
     *   event type currently defined in this specification or a new event 
     *   type.. The string must be an XML name. Any new event type must not 
     *   begin with any upper, lower, or mixed case version of the string 
     *   "DOM". This prefix is reserved for future DOM event sets. It is 
     *   also strongly recommended that third parties adding their own 
     *   events use their own prefix to avoid confusion and lessen the 
     *   probability of conflicts with other new events.
     * @param canBubbleArg Specifies whether or not the event can bubble.
     * @param cancelableArg Specifies whether or not the event's default 
     *   action can be prevented.
     */
    public void initEvent(String eventTypeArg, 
                          boolean canBubbleArg, 
                          boolean cancelableArg);

}
